In order to cool a hot granular sinter material produced in a sintering apparatus, it may be delivered onto a moving sinter cooler. There, cooling is carried out using a machine-generated air flow which may be fed from below through the hot granular sinter material placed on the cooling bed of the sinter cooler. The particle size distribution of the granular sinter material on the cooling bed may have an effect on the efficiency of the cooling, since the particle size distribution determines the resistance opposing the air flow. The effect of a resistance having a different strength in different regions of the sinter material may be that the air flow does not flow, or flows only to a lesser extent, through areas with an increased resistance and the sinter material is therefore not uniformly cooled. The effect of nonuniform cooling may be that different grains of the sinter material discharged from the sinter cooler have different temperatures. Grains with temperatures above a desired discharge temperature can cause damage to subsequent apparatus processing the cooled sinter material, for example conveyor belts and sizing screens.
The horizontal and vertical particle size distribution in the sinter material on the cooling bed of the sinter cooler may be influenced by the delivery chute through which the crushed sinter material is delivered from the sinter belt onto the sinter cooler. Certain conventional delivery chutes include a shaft delimited by side walls, with an inlet opening lying at the top for introducing the granular sinter material to be cooled, and an outlet opening lying at the bottom, through which the granular sinter material to be cooled is delivered onto the cooling bed of the sinter cooler. The outlet opening lies between side walls of the shaft and a downwardly inclined base plate of the delivery chute. Inside the shaft, a downwardly inclined inlet guide plate, by which a sliding movement extending obliquely downward is imparted to the granular material introduced into the shaft, extends on the inlet opening. Between the inlet guide plate and side walls of the delivery chute, an opening is left through which the sinter material can move following the force of gravity in the direction of the outlet opening. Below this opening, a downwardly inclined deflection plate is arranged in the shaft. Since the deflection plate has a different inclination direction to the inlet guide plate, the sinter material total flow which flows through the delivery chute has a sliding movement with a different direction imparted to it by the deflection plate. Between the deflection plate and the delivery chute shaft's side wall lying opposite the lower end of the deflection plate, an opening remains through which the sinter material can move following the force of gravity in the direction of the outlet opening. The base plate, whose inclination direction is different to that of the deflection plate, is usually arranged below this opening. When the deflection plate and the base plate respectively have opposite inclination directions to one another, then it is known that the sinter material total flow which leaves the delivery chute through the outlet opening has a particle size distribution gradient extending over the thickness of the outgoing sinter material total flow owing to segregation phenomena on the sinter-material filling of the delivery chute taking place when it passes through the delivery chute. This can be utilized in order for a moving cooling bed of the sinter cooler, lying below the outlet opening, to be loaded so that the particle size of the sinter material in the layer on the cooling bed predominantly decreases from the bottom upward as seen over the width of the cooling bed, i.e., there is a particle size distribution gradient over the thickness of the layer. A decrease in the particle size from the bottom upward may allow efficient cooling, since a cooling air flow which is delivered from below is thereby opposed with less resistance when it enters the layer. Furthermore, more heat may be stored in the particles of the sinter material with a larger particle size than in particles of the sinter material with a smaller particle size, for which reason initial contact of the cooling air flow with particles of a large particle size leads to more efficient cooling.
A disadvantage with certain conventional apparatus, however, is that the gradient of the particle size distribution may extend very nonuniformly over the total width of the moving cooling bed, or is partly absent, in particular when the sinter belt moves substantially perpendicularly to the movement direction of the sinter cooler at the delivery opening. This is because coarser-grained and therefore heavier particles of the sinter material have a greater kinetic energy in the direction of the movement direction of the sinter belt than smaller particles, and they correspondingly strike the inlet guide plate further away from the sinter belt. The coarser-grained material may arrive correspondingly more concentrated in the region of the corresponding edge of the sinter material total flow in the delivery chute. This inhomogeneous distribution may furthermore still exist on the cooling bed of the sinter cooler, for which reason uniform cooling of the sinter material by the cooling air flow may not be ensured because the resistance presented to the air flow by the sinter material may vary over the width of the cooling bed.